This randomized, placebo controlled trial will evaluate the safety and immunogenicity of Trivalent Influenza Vaccine (TIV) in HIV-infected pregnant women, dynamics of transplacental anti-influenza antibody transfer to their newborns and kinetics thereof during early infancy.

The proportion of newborns born to HIV-infected mothers with hemagglutination inhibition (HAI) antibody titers of ≥1:40 to TIV strain will be determined and compared to newborns born to TIV-vaccinated HIV-uninfected women (parallel trial) [ Time Frame: Delivery (+7 days) ] [ Designated as safety issue: No ]

Determine the proportion of newborns with hemagglutination inhibition (HAI) antibody titers of ≥1:40 to each of the three TIV strains born to HIV-infected mothers and compared to newborns born to TIV-vaccinated HIV-uninfected women

Secondary Outcome Measures:

Hemagglutinin (HA) antibody measurements in blood taken from mother and infants up to 24 weeks post delivery will be used to assess dynamics and kinetics of transplacentally acquired antibodies [ Time Frame: 24 weeks post partum ] [ Designated as safety issue: No ]

Hemagglutinin (HA) antibody measurements in blood taken from mother at birth and infants at birth, 8,16 and 24 weeks post delivery will be used to assess dynamics and kinetics of transplacentally acquired antibodies

The number of laboratory-confirmed or clinical influenza like illness cases in infants born to HIV infected mothers who received TIV or placebo will be used to determine efficacy of TIV vaccination of pregnant women against ILI in their infants [ Time Frame: 24 weeks of age ] [ Designated as safety issue: No ]

All infants (up to 24 weeks of age) born to women enrolled on trial will be assessed by study staff if they have any signs or symptoms (including fever, hospitalisation, apnea, cough, nasal catarrh/ congenstion, tachypnea) which could indicate influenza like illness. Nasopharyngeal aspirate samples collected at illness visits will be processed for viruses using real time reverse transcriptase-polymerase chain reaction (rRTPCR) assays.

The number of laboratory-confirmed influenza illnesses and clinical ILI cases in maternal participants during pregnancy and for 24 weeks post-partum will be used to assess efficacy of TIV against laboratory confirmed and clinical ILI [ Time Frame: 24 weeks ] [ Designated as safety issue: No ]

All maternal participants with signs and/ or symptoms of influenza like illness (ILI) will have nasopharyngeal and oropharyngeal swabs collected at illness visits and processed by rRTPCR assays. Participants from whom influenza virus is isolated at illness visits will be included in analysis to evaluate the efficacy of TIV against laboratory-confirmed influenza illness in mothers during pregnancy and until 24 weeks post-partum. Participants with no influenza isolated will be included in analysis of clinical ILI.

Gestational age ≥ 20 weeks to < 34 weeks documented by the approximate date of the last menstrual period and corroborated by physical exam.

Documented to be HIV-infected on two assays prior to study-enrollment.

Able to understand and comply with planned study procedures.

Provides written informed consent prior to initiation of study.

Exclusion Criteria

In HIV-infected women features of WHO clinical category 3 or 4 of AIDS at the time of enrollment.

Receipt of TIV, other than through the study, during the current influenza season documented by medical history or record.

Receipt of any live licensed vaccine ≤ 28 days or inactivated licensed vaccine ≤ 14 days prior to study-vaccine.

Receipt of a non-licensed agent (vaccine, drug, biologic, device, blood product, or medication) ≤ 28 days prior to vaccination in this study, or expects to receive another non-licensed agent before delivery unless study approval is obtained.

Any significant (in the opinion of the site investigator) acute illness and/or oral temperature greater than or equal to 38 degrees C ≤ 24 hours prior to study entry.

Use of anti-cancer systemic chemotherapy or radiation therapy ≤ 48 weeks of study enrollment, or has immunosuppression as a result of an underlying illness or treatment.

Long term use of glucocorticoids, including oral or parenteral prednisone ≥ 20 mg/day or equivalent for more than 2 consecutive weeks (or 2 weeks total) ≤ 12 weeks of study entry, or high-dose inhaled steroids (> 800 mcg/day of beclomethasone dipropionate or equivalent) ≤ 12 weeks before study entry (nasal and topical steroids are allowed).

Receipt of corticosteroids for preterm labor ≤ 14 days before study entry.(ix) Receipt of immunoglobulin or other blood products (with exception of Rho D immune globulin) ≤ 12 weeks prior to enrollment in this study or is scheduled to receive immunoglobulin or other blood products (with the exception of Rho D immune globulin) during pregnancy or for the first 24 weeks after delivery.

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Please refer to this study by its ClinicalTrials.gov identifier: NCT01306682